/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Copyright (C) 2015 ARM Limited
 */

#define pr_fmt(fmt) "psci: " fmt

#include <errno.h>
#include <seminix/arm-smccc.h>
#include <seminix/linkage.h>
#include <seminix/of.h>
#include <seminix/printk.h>
#include <seminix/psci.h>
#include <seminix/smp.h>
#include <seminix/reboot.h>
#include <asm/system_misc.h>

/*
 * While a 64-bit OS can make calls with SMC32 calling conventions, for some
 * calls it is necessary to use SMC64 to pass or return 64-bit values.
 * For such calls PSCI_FN_NATIVE(version, name) will choose the appropriate
 * (native-width) function ID.
 */
#ifdef CONFIG_64BIT
#define PSCI_FN_NATIVE(version, name)	PSCI_##version##_FN64_##name
#else
#define PSCI_FN_NATIVE(version, name)	PSCI_##version##_FN_##name
#endif

/*
 * The CPU any Trusted OS is resident on. The trusted OS may reject CPU_OFF
 * calls to its resident CPU, so we must avoid issuing those. We never migrate
 * a Trusted OS even if it claims to be capable of migration -- doing so will
 * require cooperation with a Trusted OS driver.
 */
static int resident_cpu = -1;

bool psci_tos_resident_on(int cpu)
{
    return cpu == resident_cpu;
}

struct psci_operations psci_ops = {
    .conduit = PSCI_CONDUIT_NONE,
    .smccc_version = SMCCC_VERSION_1_0,
};

typedef unsigned long (psci_fn)(unsigned long, unsigned long,
                unsigned long, unsigned long);
static psci_fn *invoke_psci_fn;

enum psci_function {
    PSCI_FN_CPU_SUSPEND,
    PSCI_FN_CPU_ON,
    PSCI_FN_CPU_OFF,
    PSCI_FN_MIGRATE,
    PSCI_FN_MAX,
};

static u32 psci_function_id[PSCI_FN_MAX];

#define PSCI_0_2_POWER_STATE_MASK		\
                (PSCI_0_2_POWER_STATE_ID_MASK | \
                PSCI_0_2_POWER_STATE_TYPE_MASK | \
                PSCI_0_2_POWER_STATE_AFFL_MASK)

#define PSCI_1_0_EXT_POWER_STATE_MASK		\
                (PSCI_1_0_EXT_POWER_STATE_ID_MASK | \
                PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)

static u32 psci_cpu_suspend_feature;

static inline bool psci_has_ext_power_state(void)
{
    return psci_cpu_suspend_feature &
                PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
}

static inline bool psci_power_state_loses_context(u32 state)
{
    const u32 mask = psci_has_ext_power_state() ?
                    PSCI_1_0_EXT_POWER_STATE_TYPE_MASK :
                    PSCI_0_2_POWER_STATE_TYPE_MASK;

    return state & mask;
}

static inline bool psci_power_state_is_valid(u32 state)
{
    const u32 valid_mask = psci_has_ext_power_state() ?
                   PSCI_1_0_EXT_POWER_STATE_MASK :
                   PSCI_0_2_POWER_STATE_MASK;

    return !(state & ~valid_mask);
}

static unsigned long __invoke_psci_fn_hvc(unsigned long function_id,
            unsigned long arg0, unsigned long arg1,
            unsigned long arg2)
{
    struct arm_smccc_res res;

    arm_smccc_hvc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
    return res.a0;
}

static unsigned long __invoke_psci_fn_smc(unsigned long function_id,
            unsigned long arg0, unsigned long arg1,
            unsigned long arg2)
{
    struct arm_smccc_res res;

    arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
    return res.a0;
}

static int psci_to_linux_errno(int err)
{
    switch (err) {
    case PSCI_RET_SUCCESS:
        return 0;
    case PSCI_RET_NOT_SUPPORTED:
        return -EOPNOTSUPP;
    case PSCI_RET_INVALID_PARAMS:
    case PSCI_RET_INVALID_ADDRESS:
        return -EINVAL;
    case PSCI_RET_DENIED:
        return -EPERM;
    };

    return -EINVAL;
}

static u32 psci_get_version(void)
{
    return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
}

static int psci_cpu_suspend(u32 state, unsigned long entry_point)
{
    int err;
    u32 fn;

    fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
    err = invoke_psci_fn(fn, state, entry_point, 0);
    return psci_to_linux_errno(err);
}

static int psci_cpu_off(u32 state)
{
    int err;
    u32 fn;

    fn = psci_function_id[PSCI_FN_CPU_OFF];
    err = invoke_psci_fn(fn, state, 0, 0);
    return psci_to_linux_errno(err);
}

static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
{
    int err;
    u32 fn;

    fn = psci_function_id[PSCI_FN_CPU_ON];
    err = invoke_psci_fn(fn, cpuid, entry_point, 0);
    return psci_to_linux_errno(err);
}

static int psci_migrate(unsigned long cpuid)
{
    int err;
    u32 fn;

    fn = psci_function_id[PSCI_FN_MIGRATE];
    err = invoke_psci_fn(fn, cpuid, 0, 0);
    return psci_to_linux_errno(err);
}

static int psci_affinity_info(unsigned long target_affinity,
        unsigned long lowest_affinity_level)
{
    return invoke_psci_fn(PSCI_FN_NATIVE(0_2, AFFINITY_INFO),
                  target_affinity, lowest_affinity_level, 0);
}

static int psci_migrate_info_type(void)
{
    return invoke_psci_fn(PSCI_0_2_FN_MIGRATE_INFO_TYPE, 0, 0, 0);
}

static unsigned long psci_migrate_info_up_cpu(void)
{
    return invoke_psci_fn(PSCI_FN_NATIVE(0_2, MIGRATE_INFO_UP_CPU),
                  0, 0, 0);
}

static void set_conduit(enum psci_conduit conduit)
{
    switch (conduit) {
    case PSCI_CONDUIT_HVC:
        invoke_psci_fn = __invoke_psci_fn_hvc;
        break;
    case PSCI_CONDUIT_SMC:
        invoke_psci_fn = __invoke_psci_fn_smc;
        break;
    default:
        WARN(1, "Unexpected PSCI conduit %d\n", conduit);
    }

    psci_ops.conduit = conduit;
}

static int get_set_conduit_method(struct device_node *np)
{
    const char *method;

    pr_info("probing for conduit method from DT.\n");

    if (of_property_read_string(np, "method", &method)) {
        pr_warn("missing \"method\" property\n");
        return -ENXIO;
    }

    if (!strcmp("hvc", method)) {
        set_conduit(PSCI_CONDUIT_HVC);
    } else if (!strcmp("smc", method)) {
        set_conduit(PSCI_CONDUIT_SMC);
    } else {
        pr_warn("invalid \"method\" property: %s\n", method);
        return -EINVAL;
    }
    return 0;
}

static void psci_sys_reset(enum reboot_mode mode, const char *cmd)
{
    invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
}

static void psci_sys_poweroff(void)
{
    invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
}

static int __init psci_features(u32 psci_func_id)
{
    return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
                  psci_func_id, 0, 0);
}

static void __init psci_init_system_suspend(void)
{
}

static void __init psci_init_cpu_suspend(void)
{
    int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);

    if (feature != PSCI_RET_NOT_SUPPORTED)
        psci_cpu_suspend_feature = feature;
}

/*
 * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
 * return DENIED (which would be fatal).
 */
static void __init psci_init_migrate(void)
{
    unsigned long cpuid;
    int type, cpu = -1;

    type = psci_ops.migrate_info_type();

    if (type == PSCI_0_2_TOS_MP) {
        pr_info("Trusted OS migration not required\n");
        return;
    }

    if (type == PSCI_RET_NOT_SUPPORTED) {
        pr_info("MIGRATE_INFO_TYPE not supported.\n");
        return;
    }

    if (type != PSCI_0_2_TOS_UP_MIGRATE &&
        type != PSCI_0_2_TOS_UP_NO_MIGRATE) {
        pr_err("MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
        return;
    }

    cpuid = psci_migrate_info_up_cpu();
    if (cpuid & ~MPIDR_HWID_BITMASK) {
        pr_warn("MIGRATE_INFO_UP_CPU reported invalid physical ID (0x%lx)\n",
            cpuid);
        return;
    }

    cpu = get_logical_index(cpuid);
    resident_cpu = cpu >= 0 ? cpu : -1;

    pr_info("Trusted OS resident on physical CPU 0x%lx\n", cpuid);
}

static void __init psci_init_smccc(void)
{
    u32 ver = ARM_SMCCC_VERSION_1_0;
    int feature;

    feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);

    if (feature != PSCI_RET_NOT_SUPPORTED) {
        u32 ret;
        ret = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
        if (ret == ARM_SMCCC_VERSION_1_1) {
            psci_ops.smccc_version = SMCCC_VERSION_1_1;
            ver = ret;
        }
    }

    /*
     * Conveniently, the SMCCC and PSCI versions are encoded the
     * same way. No, this isn't accidental.
     */
    pr_info("SMC Calling Convention v%d.%d\n",
        PSCI_VERSION_MAJOR(ver), PSCI_VERSION_MINOR(ver));

}

static void __init psci_0_2_set_functions(void)
{
    pr_info("Using standard PSCI v0.2 function IDs\n");
    psci_ops.get_version = psci_get_version;

    psci_function_id[PSCI_FN_CPU_SUSPEND] =
                    PSCI_FN_NATIVE(0_2, CPU_SUSPEND);
    psci_ops.cpu_suspend = psci_cpu_suspend;

    psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
    psci_ops.cpu_off = psci_cpu_off;

    psci_function_id[PSCI_FN_CPU_ON] = PSCI_FN_NATIVE(0_2, CPU_ON);
    psci_ops.cpu_on = psci_cpu_on;

    psci_function_id[PSCI_FN_MIGRATE] = PSCI_FN_NATIVE(0_2, MIGRATE);
    psci_ops.migrate = psci_migrate;

    psci_ops.affinity_info = psci_affinity_info;

    psci_ops.migrate_info_type = psci_migrate_info_type;

    arm_pm_restart = psci_sys_reset;

    pm_power_off = psci_sys_poweroff;
}

/*
 * Probe function for PSCI firmware versions >= 0.2
 */
static int __init psci_probe(void)
{
    u32 ver = psci_get_version();

    pr_info("PSCIv%d.%d detected in firmware.\n",
            PSCI_VERSION_MAJOR(ver),
            PSCI_VERSION_MINOR(ver));

    if (PSCI_VERSION_MAJOR(ver) == 0 && PSCI_VERSION_MINOR(ver) < 2) {
        pr_err("Conflicting PSCI version detected.\n");
        return -EINVAL;
    }

    psci_0_2_set_functions();

    psci_init_migrate();

    if (PSCI_VERSION_MAJOR(ver) >= 1) {
        psci_init_smccc();
        psci_init_cpu_suspend();
        psci_init_system_suspend();
    }

    return 0;
}

typedef int (*psci_initcall_t)(const struct device_node *);

/*
 * PSCI init function for PSCI versions >=0.2
 *
 * Probe based on PSCI PSCI_VERSION function
 */
static int __init psci_0_2_init(struct device_node *np)
{
    int err;

    err = get_set_conduit_method(np);

    if (err)
        goto out_put_node;
    /*
     * Starting with v0.2, the PSCI specification introduced a call
     * (PSCI_VERSION) that allows probing the firmware version, so
     * that PSCI function IDs and version specific initialization
     * can be carried out according to the specific version reported
     * by firmware
     */
    err = psci_probe();

out_put_node:
    return err;
}

/*
 * PSCI < v0.2 get PSCI Function IDs via DT.
 */
static int __init psci_0_1_init(struct device_node *np)
{
    u32 id;
    int err;

    err = get_set_conduit_method(np);

    if (err)
        goto out_put_node;

    pr_info("Using PSCI v0.1 Function IDs from DT\n");

    if (!of_property_read_u32(np, "cpu_suspend", &id)) {
        psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
        psci_ops.cpu_suspend = psci_cpu_suspend;
    }

    if (!of_property_read_u32(np, "cpu_off", &id)) {
        psci_function_id[PSCI_FN_CPU_OFF] = id;
        psci_ops.cpu_off = psci_cpu_off;
    }

    if (!of_property_read_u32(np, "cpu_on", &id)) {
        psci_function_id[PSCI_FN_CPU_ON] = id;
        psci_ops.cpu_on = psci_cpu_on;
    }

    if (!of_property_read_u32(np, "migrate", &id)) {
        psci_function_id[PSCI_FN_MIGRATE] = id;
        psci_ops.migrate = psci_migrate;
    }

out_put_node:
    return err;
}

static const struct of_device_id psci_of_match[] __initconst = {
    { .compatible = "arm,psci",	.data = psci_0_1_init},
    { .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
    { .compatible = "arm,psci-1.0",	.data = psci_0_2_init},
    {},
};

int __init psci_dt_init(void)
{
    struct device_node *np;
    const struct of_device_id *matched_np;
    psci_initcall_t init_fn;

    np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);

    if (!np || !of_device_is_available(np))
        return -ENODEV;

    init_fn = (psci_initcall_t)matched_np->data;
    return init_fn(np);
}
